European Aero Engine Companies assisted by National Research Establishments have a long and successful record in the design, development and manufacture of engines for high performance military fighter aircraft.

Because the cost of developing and producing a new aero engine is now so great, it has become increasingly impracticable for individual European nations to embark on such projects alone. This has resulted in recent years in a number of collaborative European engine programmes. As Fig. 1 shows, the range of European military turbofan engines now in service is largely the result of such collaboration amongst various European countries, and compares with the much more limited US involvement in design collaboration. Figure 1 also shows that the thrust range covered by European military turbofans is very comparable to that of engines of US manufacture.

The history of the European Transonic Wind-tunnel is briefly described.

After a discussion of the tunnel specifications and performance, a general description of the facility is provided.

The results of an investigation into the expected future use of the tunnel are summarised.

Information on the pilot tunnel PETW is presented, as well as some results on flow quality obtained in an aerodynamic test rig.

Finally, some reference is made to a supporting programme on cryogenic technology.

An elasticity solution is presented for the three layered all round simply supported rectangular plate subjected to a uniformly distributed normal load. Numerical results have been obtained by selecting parameters such that they are applicable for sandwich plates. A detailed comparison of these results has been made with the results of sandwich plate theory developed by Monforton and Ibrahim.

A unified account is presented of the various inviscid models used to represent three-dimensional vortex flows in aerodynamics; essentially those relying on vortex sheets and linevortices. Recent developments in extending the scope, accuracy, and stability of these models are described. An evaluation of their relative strengths and weaknesses suggests that the different models all have continuing roles to play. It is claimed that vortex modelling has come of age, in the sense that we can now learn about the real world from the behaviour of models, after decades of trying to make the models conform with reality.

The large amplitude wing-rock of a ground attack aircraft was investigated by the use of a small perturbation, linear stability analysis and a non-linear simulation of the aircraft dynamics. The linear stability analysis compared the results from a complete 6 degrees-of-freedom (DOF) coupled equation set with the results obtained using a 3-DOF dynamic stability axis set. The results showed an oscillatory instability that was caused by frequency coalescence of the primary pitch and yaw modes.

The simulation produced a rolling motion similar in nature to wing-rocks experienced in flight. The large amplitude oscillation was generated by the non-linear variations of the aerodynamic loads rather than by the instability predicted by the linearised dynamics. Specifically, the appearance of nonzero lateral moments at zero sideslip as well as shock-induced jumps in the rolling moment against sideslip curves were major contributors to the motion. These features of the static aerodynamic data are thus considered better warnings of the possibility of large amplitude wing-rock than is the negatively damped Dutch roll oscillation predicted by the linearised analysis.

A simple nacelle comprising a thin cylindrical shell of uniform diameter enclosing an engine, idealised by an actuator disc, is analysed at incidence to a low speed uniform stream for various engine mass flow rates on the basis of a vortex lattice model.

Loadings along the length of the nacelle are calculated, together with the overall normal force, the leading edge thrust on the nacelle nose, and the overall pitching moment. Most of the loading arises over the front part of the nacelle, which is well known. However, there is a significant contribution to the overall pitching moment from the nacelle nose for a nacelle, with engine, at incidence; this effect is absent from a through flow nacelle without an engine. Formulae for ∂CN/∂α and ∂CM/∂α as functions of mass flow rate are derived for a length/diameter ratio of 3:0.

A method is given for the calculation of incompressible inviscid flow through non-axisymmetric contracting ducts with rectangular cross-sections. The method is based on a finite difference approximation to Laplace's equation and solved by the method of successive over relaxation. In an attempt to provide practical criteria for the design of such contractions, the flows through a series of contraction shapes were calculated, each shape being based on a pair of matched elliptic arcs. This permitted choice of such parameters as length, local (ie two-dimensional) contraction ratio, position and magnitude of the maximum slope. It was found that reducing the length of the contraction also reduced its effective length, although increasing the effects of overshoot and undershoot. This could be compensated for by designing a contraction with a steep maximum slope which with associated low curvatures at entrance and exit reduced the values of overshoot and undershoot. The axial positions of maximum slope on wall and roof should be the same.

The predictions of the numerical method were tested against experiment and, in general, satisfactory comparisons were obtained.

It is both a privilege and a pleasure to be asked to contribute to an edition of the Aeronautical Journal to celebrate Professor Alec Young's 70th birthday. He has been my mentor for nearly a quarter of a century.

The subject of integral prediction methods for boundary layers is one with which Alec Young has long been associated. Starting with a method for laminar compressible flow he has guided the development of, amongst others, integral methods for compressible laminar flow with heat transfer, three-dimensional laminar flow, three-dimensional turbulent flow and flows with pressure gradients normal to the surface.

This paper attempts to describe the integral methods for compressible turbulent boundary layers which are most widely used in aerodynamic design and to discuss the application of inverse integral methods to three-dimensional separated flows.

An experimental investigation has been carried out to compare the effects of sweep direction upon the aerodynamic characteristics of three wing planforms. The wings have biconvex aerofoil sections which allow them to be tested in both the forward-swept and backward-swept configurations without changing the section profile. Measurements of lift, drag and pitching moment have been made for angles of incidence in the range —5° to +50° at a mean chord Reynolds number of approximately 1·5 × 105 and a Mach number of 0·1. To complement the force and moment data a comprehensive series of oil-flow visualisations are also presented. In addition the aerodynamic characteristics of simple strakes (wing root fillets) have been studied for both the swept-forward and swept-back configurations.

The following papers describe developments which are projected in the various areas of the aero-engine scene. I do not wish to pre-empt or overlap these papers but instead propose to attempt to paint a general strategic picture.

Both commercial and military aviation have been transformed by the emergence of the jet engine in the early 1940s. On the civil side, aircraft have become larger, more economical, faster, more comfortable, more reliable and safer. On the military side, the jet engine has made supersonic operation possible and has enabled aircraft size to be reduced even with enhanced mission capability. Also, the small turboshaft engine has enabled the helicopter to be developed to be an integral part of any defence system.

Until the mid-1960s, the civil engines were determined by a need to progressively improve SFC, reduce noise, increase reliability and, at the same time, increase thrust (Fig. 1). We saw only minor changes in cycle and configuration up to the low bypass ratios of JT3D, JT8, Conway and Spey. In more recent times, the large fan engines, JT9, CF6 and RB 211, led to a step-change in both SFC and noise level and the subsequent 10-15 years has yielded progressive refinements of these engines.

The unsteady planar flow of inviscid compressible fluid past an oscillating aerofoil is considered. Many recent computational studies have experienced difficulties in obtaining accurate, or any, results at medium or higher frequencies of oscillation. This may well be due to the emergence of multi-scaling and multi-regions according to the present analytical study which concentrates on the large frequency properties of the linearised flowfield. Multi-scaled dependence in the solution is found to occur in both the streamwise and transverse directions. Comparisons are made with computational results.

As a member of the International group who set up the von Karman Institute for Fluid Dynamic (known at that time as the Training Centre for Experimental Aerodynamics — TCEA) Professor A. D. Young participated actively in the Institute's programme. After the death of Dr von Karman in 1963, he was nominated Chairman of the VKI Board of Directors, and still holds this position.

It is clear that the goals of the Institute, as envisaged by Dr von Karman, have been successfully met. After the first few challenging years under his leadership, it was essential to ensure that the scientific reputation of the Institute continued to be strengthened. The VKI is now recognised as a major establishment in its own right with a very high scientific reputation.

The aerodynamic performance of man-powered aircraft has been considered by a number of authors including (Lilley and Spillman (1960), Lissaman et al (1979), Wimpenny (1979)). The present paper attempts a simplistic approach and gives a comparison between these simple formulae and the performance of the various designs of man-powered aircraft for which design information is available, or from measured data in flight. The latter information is generally in agreement with that tabulated in Reay (1977) and Sherwin (1971). The data on the Gossamer Condor and Gossamer Albatross were obtained from Lissaman et al (1979) and Jex and Mitchell (1982). A review of achievements in man-powered flight before the Channel crossing was given by Clark (1978).

The paper also discusses briefly the performance of manpowered aircraft with energy storage for assisted take-off and as a contribution for cruising flight. It is hoped the paper will give a broad picture of the aerodynamic performance challenge set by the Kremer (1983) World Speed Record Competition.

Wind tunnel tests have been made on the effect of bottom wall and sidewall fences of various sizes and combinations in reducing the swirl of an S-duct at high angle of attack. It is shown that large reductions can be made: in some cases the swirl is eliminated or even reversed. Fences of modest size can be chosen to combine a large swirl reduction with an improvement of the total pressure distortion at high incidence and only a small effect on mean pressure recovery at low incidence. Some further observations are made on the nature of the general swirl phenomenon.

It has long been pointed out by Gray that large aquatic animals, notably the dolphin, have been observed to achieve speeds which appear to be far beyond their muscular capabilities, unless they somehow experience laminar flow. Many workers have puzzled over this problem, and various possibilities have been propounded. In particular Wu has carried out a long theoretical analysis of the swimming of a slender fish in two dimensions, and he mentions the prospect of the zero momentum wake.

The principle of the zero momentum wake (or boundary layer propulsion, as it is sometimes called) has often attracted the attention of aircraft propulsion engineers. A small wind tunnel experiment by Göbel and Oehler is of interest. They took a circular sieve, representing profile drag, and set this in relation to a propeller of the same diameter as the sieve. The sieve and the propeller were set side-by-side on a bar, and the power required to propel the model was measured. Then the sieve and the propeller were set in tandem, with the sieve in front of the propeller, and the power required measured again. The power required for the tandem arrangement was found to be significantly less than that required for the side-by-side arrangement.

The governing differential equations of motion for flexural vibrations of a doubly curved sandwich panel consisting of stiff elastic face layers sandwiching soft viscoelastic core have been derived, considering extension and bending deformations of the face layers and shear deformations of the core, using variational principles. Solution for panel with simply supported edges is assumed in series summation form and the correspondence principle of linear viscoelasticity is applied for evaluation of resonance frequencies and associated system loss factors. The effects of variations of geometrical and material parameters on the resonance frequencies and associated system loss factors are reported.

The Euler equations are proving to be an appropriate model for in viscid vortex flow. This paper demonstrates the range of this model’s applicability by presentation of flowfields computed around a number of different wings with either sharp or rounded edges at transonic and supersonic speeds. The emphasis here is on the physics of the flow model rather than the numerical aspects of the solution method. The results display both expected as well as unexpected vortex phenomena and they indicate the value of this computational tool. Particular attention is paid to the wake regions.

The recognition of the political importance of energy supply, inefficient energy usage and its adverse ecological impact combined to produce rapidly inflating energy prices which in turn contributed to an industrial slump. With this platform of a decade of uncertainty, predicting future requirements is, to say the least, somewhat problematical. One thing, however, that seems certain is that the future will offer more free time for the population generally which, together with a continuously improving standard of living, will promote cost effective travel as an essential ingredient to satisfying leisure demand. The most cost effective and energy efficient means of travel over significant distances, and certainly over water, is the 0·70/0·85 Mach No subsonic aircraft. We have, therefore, to speculate about the relative operational priorities of the powerplant to be utilised.

The vortex lattice model developed in Part I has been extended to estimate the overall loads and moments on a cylindrical nacelle alone and on a cylindrical nacelle, enclosing an engine, when the configuration oscillates in simple harmonic motion in an air stream. Results are presented for a range of frequency parameter and thrust conditions. Although the problem is properly posed for low speed flow through the ‘engine’, there is doubt over the model formulation when density changes need to be accounted for.

Small gas turbine engines are used in a large variety of applications (Fig. 1) and therefore any model range should accommodate as many of these roles as possible to secure a broad market base. First and second generation engines were launched initially against a requirement for military helicopters and small to medium sized turboprop powered aircraft. However due to the search for oil the role of the helicopter has expanded into offshore oil exploration whilst the better fuel efficiency of the turboprop powered aircraft relative to the turbofan will ensure its future for short range commuter aircraft. Additionally with further improvements in helicopter and engine reliability and costs, the helicopter will be used increasingly in the Air Taxi role to provide rapid transportation over short distances to avoid ground traffic congestion or particular geographical features that preclude short transit times. Specifically the use of the helicopter to connect airports with each other and city centres is becoming a real possibility as reliability improves and operational costs reduce.